1. Field of the Invention
The present invention relates to a method of, and an apparatus for, sewing a slide fastener to a pair of fabric pieces, such as, for example, of a curtain, a tent or a garment.
2. Prior Art
Conventionally, for attaching a slide fastener to a pair of fabric pieces on a sewing machine, a slider is manually moved to a bottom end portion of the slide fastener to uncouple a pair of opposed fastener stringers of the slide fastener except at their bottom end portions. The uncoupled stringers are introduced, as superimposed over the respective fabric pieces, to a sewing station of the sewing machine from a top end portion of the slide fastener, while the fastener stringers are being twisted in mirror symmetry with respect to the longitudinal centerline of the slide fastener so that a pair of initially opposed rows of coupling elements is directed away from one another. The pair of fastener stringers are sewn by a pair of reciprocating sewing needles to the respective fabric pieces from the top end portion of the slide fastener in the sewing station.
Such conventional sewing practice is disadvantageous however in that the two substantially fully uncoupled fastener stringers are likely to displace from one another in a longitudinal direction due to tensioning forces applied thereto during sewing operation. Because of this relative displacement, the fastener stringers with the fabric pieces sewn thereto cannot be coupled together smoothly and quickly. When fully closed, the slide fastener having such displaced stringers becomes wavy or undulated, making the fabric pieces become defective from an aesthetic view. The conventional sewing practice is not suitable in applications wherein the pair of fabric pieces have design patterns printed thereon and a mutual matching or alignment of such design patterns across the slide fastener is a major requirement. Due to the reliance on time-consuming manual opening of the slide fastener, sewing efficiency is very low. When sewing a remarkably long slide fastener, it occurs likely that a pair of opposed fastener stringers is unintentionally twisted in asymmetry. The fastener stringers sewn to the respective fabric pieces cannot be coupled together smoothly due to occurrence of an objectionable inward bulge of the fabric pieces between the opposed stringers.
Typical examples of the foregoing sewing practice are disclosed in Japanese Utility Model Publication No. 47-16295 and Japanese Patent Publication No. 48-31335.